Two-dimensional identification (2DID) codes, such as QR codes and Data Matrix codes, are types of a matrix barcode that is widely used for product tracking and providing a variety of information. QR codes include filled darkened squares (black squares) arranged within a square grid on a light background and are suitable for high-speed acquisition by an imaging device, such as a camera. Typical square grid patterns range from 11 to 177 squares per row or column. Patterns in the horizontal and the vertical components of the acquired image can reveal or activate the coded information, such as for commercial tracking, entertainment and transport ticketing, product labeling, product marketing, mobile phone tagging, couponing, displaying text, adding vCard contact information, opening an URL or URI, or composing email or text messages. The QR code is covered by an ISO standard, and its use is license free. QR code generating websites and apps are widely available so users can generate and print their own QR codes for others to scan. (See http://en.wikipedia.org/wiki/QR_code.) An exemplary QR code is shown in FIG. 1.
Data Matrix codes are also covered by several ISO and IEC standards and are license free for many applications. See http://en.wikipedia.org/wiki/Data_Matrix. Data Matrix code-generating resources are also widely available. An exemplary Data Matrix code generated using http://datamatrix.kaywa.com is shown in FIG. 2.
Methods exist for marking these 2DID codes on various materials and in many different sizes. For example, some 2DID codes can be printed on labels using traditional print technology, engraved into metal, and carved into tombstones.